Identification of a specific telomere terminal transferase activity in tetrahymena extracts
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Discussion
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Implication
Biochemical study reveals a novel telomere terminal transferase in Tetrahymena extracts that adds tandem repeats, suggesting a mechanism for eukaryotic chromosome end replication.
Key Points
- Investigate the enzymatic mechanism responsible for synthesizing and adding telomeric DNA repeats onto chromosome ends in Tetrahymena.
- Incubated Tetrahymena cell-free extracts with synthetic single-stranded DNA primers matching Tetrahymena, yeast, and non-telomeric sequences in the presence of deoxynucleotides.
- Tested enzymatic activity sensitivity to heat and proteinase K, dependence on alpha-type DNA polymerase, and activity levels across vegetative growth versus macronuclear development stages.
- Cell-free extracts efficiently synthesized tandem TTGGGG repeats onto Tetrahymena and yeast telomeric primers, but not onto complementary or nontelomeric oligomers, requiring only micromolar concentrations of dGTP and dTTP.
- The elongation activity was abolished by heat and proteinase K treatment, functioned independently of endogenous DNA and alpha-type DNA polymerase, and was notably higher during macronuclear development than during vegetative cell growth.
Cite This Study
Greider et al. (1985) studied this question.